The invention relates to a fluid separating apparatus for separating liquids and solids from a multicomponent fluid. Such apparatuses are used in water purification, pulp and sludge thickening as well as in de-ashing or fractionation, particularly in the paper industry.
Conventional fluid separating apparatuses operate according to different principles for separating the clear fluid from the various solids. The separation principle depends on the expected composition of the multicomponent fluid.
U.S. Pat. No. 4,274,963 discloses a generic separating apparatus. This apparatus is typically used for suspensions of recovered waste paper, which contain paper fibers, light contaminants (plastics, wood) and heavy contaminants (e.g., glass, sand and metal particles). Due to the specific weight difference, the heavy contaminants could actually be easily separated from the water by means of this sedimentation apparatus. The separation, however, would work only if no light contaminants were present since the fibers and plastics persistently impede or interfere with the sedimentation process. The light contaminants further form a scum layer on the open surface inside the filter tank, which would impede or even clog the inflow into the machine.
On the other hand, the light contaminants could be readily separated from the water by a so-called disk thickener. In the presence of heavy contaminants, however, e.g., sand and glass, such a disk thickener is subject to very high wear. As a result a disproportionate amount of maintenance and repair would be required and the overall life of the entire apparatusxe2x80x94and thus its efficiencyxe2x80x94would be clearly reduced. In other words, the separating process is inefficient irrespective of whether an apparatus according to the generic publication is fluidically arranged in front of or behind a disk thickener.
Based thereon the object of the invention is to define a fluid separating apparatus in accordance with the preamble of claim 1, which operates without wear and effectively separates a multicomponent fluid into three different fractions, a clear liquid, a sludge fraction and a particle fraction. The aim is a high-quality separation of the multicomponent fluid into three different fractions, the clear liquid, a sludge fraction and a particle fraction.
According to the invention, this object is attained by the features set forth in claim 1. Advantageous further developments of the idea underlying the invention are set forth in the dependent claims.
Through the feature combination of claim 1, the light contaminants are continuously discharged via the rotary filter unit. This prevents the light particles from hindering sedimentation so that the heavy contaminants are reliably separated in the sedimentation space.
The inventionxe2x80x94in contrast to prior art machines connected in seriesxe2x80x94achieves a substantially clearer separation of the two solids fractions into heavy particles (usually inorganic and suitable for disposal in landfills) and light particles (usually organic and either suitable for incineration or recyclable in the process). On the other hand the clear liquid has undergone a substantially greater degree of clarification. At the same time, the apparatusxe2x80x94compared to the aforementioned fictitious series connection of two individual apparatusesxe2x80x94is less prone to malfunctions and therefore economically more efficient.
An essential advantage of the arrangement according to the invention is that it makes it possible to separate a fluid/solid mixture into three different fractions in one compact structure. The apparatus according to the invention is configured in such a way that it rarely ever clogs or becomes inoperable. The arrangement permits a very high fluid throughput.